Having some problems threading with a DSPMC and Mach3. Can not seem to get a clean cut and consistent pitch to the point where the thread is a complete mess. The thread looks to start ok in the first few passes but as the program continues the pitch gets lost to the point where the tool looks to be lagging behind. Trying to recut the thread on the same piece of stock starts the thread in a different position radially then the original cut was performed.

Setup is as follows:

- Spindle encoder 1000ppr set to 4000 on config screen- Cutting rpm is 210- Thread to cut is 40 x 1.5mm x about 12mm long- The lathe setup units are in metric but the program file is imperial (G20)

Tried the following versions of Mach3, DSPMC plupin, SyncRay file, and FPGA files and all gave the similar results.

- Tried plugin 4.0.9.0 with SyncRaySG-8.11 and fpga DSPMC-E104 also tried plugin 4.2.0.0 with SyncRaySG-9.05 and DSPMC_E901_FPGA, same results- Tried different versions of Mach3 (v66, v62, and v57) all same results

Tried the special threading logic inside plugin 4.2.0.0 as well with no change in results.

- Use Spindle feedback in sync mode must be checked- Spindle Speed Averaging must be checked- Must be in exact stop mode (G61) vs constant velocity mode (G64)- Debounce interval = 0- Index debounce = 100- Special threading logic inside plugin 4.2.0.0 is required to get proper thread pitch (#1000 = 7762 and #1001 = 1 before G32). Without it the pitch will be finer than expected.- Use DSPMC_E901_FPGA- In the DSPMC plugin, threading feedback sampling time = 50- Currently using Mach3 v66

Using the above settings gave consistent pitch and good thread form

I have not tried G76 yet but I suspect the results will be the same as G32.

My original mistake was thinking the DSPMC took over threading in a similar way it does for rigid tapping based on the special code that needed to be on. What I realized is that Mach3 still has control of the thread and the DSPMC is essentially following orders.

I hope anyone else using a DSPMC with Mach3 on a lathe finds this useful.